Haul trucks, both on and off highway, include three axles a forward axle, a center axle and a rear axle. Output from a power source is supplied to all three axles via drive shafts. A transmission is directionally engaged to power the axle assemblies. While the forward axle assembly may be operatively engaged/disengaged through the use of a drop box to allow the truck to be operated in an all-wheel drive mode. Each axle assembly includes a differential gear set that includes a pinion gear in mesh with a ring gear. The pinion gears of the forward and rear axle assemblies are generally directly driven via drive shafts through splined connections via a yoke. While the center axle includes a through shaft that drives a series of gears to drive the pinion gear and lastly the differential wheel.
The through shaft is supported at each end by a pair of bearings. One pair of bearings support a forward end of the through shaft and an additional pair of bearings support a rear end of the through shaft.
There is a need to provide lubrication to components of the center axle assembly and particularly the support bearings for the through shaft. Conventional methods of lubricating the bearings include the use of splash lubrication from the pinion gear and bevel gear during operation of the haul truck. However, due to location of each bearing splash lubrication from the pinion gear and the bevel gear rotation cannot reach all of the bearings at the front end of the center axle assembly. A known method for lubricating components of the center axle assembly is shown in U.S. Pat. No. 7,258,641 issued to Green et al on Aug. 21, 2007 and assigned to Dana Corporation. In the “641” patent, lubricant splashed from the ring gear is collected and is then distributed by a bearing supporting the output side gear for rotation within the housing for the assembly. The bearing directs lubricant to the differential gears where seals and/or close tolerances retain the lubricant and allow it to flow to the surfaces of the input shaft and the helical side gear disposed about the input shaft. The output side gear disposed about the output shaft may also include a passage allowing lubricant to flow through the gear to the bearing surfaces of the output shaft and output side gear. Not all center axle assemblies have the differential gears and close tolerances are costly to manufacture.
The present disclosure is directed to overcoming one or more of the deficiencies as set forth above.